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Astronomical Data Analysis Software and Systems XIII ASP Conference Series, Vol. 314, 2004 F. Ochsenbein, M. Al len, and D. Egret, eds.

AstroCat/CVcat: A catalogue on Cataclysmic Variables based on a new framework for online interactive astronomical databases
Fabian Euchner, Alexander Pollmer, Klaus Beuermann UniversitЁ -Sternwarte, Geismarlandstr. 11, D-37083 GЁ ats ottingen, Germany Boris T. GЁ sicke an Department of Physics, University of Warwick, Coventry CV4 7AL, UK Jens Kube Stiftung Alfred-Wegener-Institut fur Polar- und Meeresforschung in der Ё Helmholtz-Gemeinschaft, Koldewey-Station, N-9173 Ny-° Alesund, Norway Abstract. We report on the progress of the development of CVcat, an interactive catalogue on Cataclysmic Variables, which is the first application based on AstroCat, a general framework for the installation and maintenance of web-based interactive astronomical databases. Registered users can contribute directly to the catalogue content by adding new ob jects, ob ject properties, literature references, and annotations. The scientific quality control of the catalogue is carried out by a distributed editorial team. Searches in CVcat can be performed by ob ject name, classification, certain properties or property ranges, and coordinates. Search results can be retrieved in several output formats, including XML. Old database states can be restored in order to ensure the citability of the catalogue. Furthermore, CVcat is designed to serve as a repository for reduced data from publications. Future prospects include the integration of AstroCat-based catalogues in the international network of Virtual Observatories.

1. 1.1.

AstroCat ­ a new concept for astronomical catalogues Motivation

Traditionally, in astronomy the availability of online digital information is excellent with respect to scientific publications (NASA's Astrophysics Data System, arXiv.org preprint server) and raw observational data. With the development of the AstroCat software we intend to fill the gap between these two categories by enabling astronomers to set up interactive astronomical catalogues for reduced and inferred data (Fig. 1). 578 c Copyright 2004 Astronomical Society of the Pacific. All rights reserved.


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abstraction, interpretation

scientific publication

ADS, online journals

inferred data, e.g. mass, distance

no interactive catalogue available

reduced data, e.g. light curves, spectra

raw data

data archives

Figure 1. Level of abstraction and digital availability of astronomical information.

1.2.

Ob jectives

AstroCat is a software framework for the implementation of a new type of webbased interactive astronomical catalogues. AstroCat -based catalogues are intended to hold information on the physical properties of astronomical ob jects of a specific class. We provide the possibility to account for fine-grained hierarchical sub-classifications of the selected ob jects. The information contained in the catalogue should be gathered from trustworthy publications, preferably from refereed papers. The scientific quality control is performed by users who assumed editorial duties. If available, a hyperlink to an electronic version of the referenced publication should be given for each catalogue entry (e.g. via the ADS, the astro-ph preprint server, or online journals like the Information Bulletin on Variable Stars ). We will also provide the possibility for authors to share reduced data (spectra, light curves, images, etc.) from their publications with the community of users. Our new concept of astronomical catalogues and the differences to existing catalogues are best characterized by the terms interactivity, up-to-dateness and accessibility : Interactivity: All registered users may contribute to the database content by adding new data. The reliability of the data is ensured by an editorial team which is allowed to modify catalogue entries. We achieve a high level of ob jectiveness by allowing for several entries per property. We also allow for detailed annotations on the catalogue entries. Up-to-dateness: Most `classical' catalogues are updated only in irregular and/or lengthy intervals. In AstroCat -based catalogues all changes to the database are made instantly visible to the users. To ensure the citability of the catalogue, we provide a mechanism for restoring previous states of the catalogue content. Accessibility: The web-based character allows for simple but powerful searching on the database via a web browser. The query results can be formatted in various user-definable styles. We also provide the possibility to retrieve the query


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Euchner, Pollmer, Gansicke, Kube & Beuermann Ё

results in XML format in order to supply the user with semantically enriched data. Additional information on the AstroCat/CVcat pro ject can be found at our web page1 . At this location, we provide an online discussion forum2 where comments on the pro ject can be placed. 2. CVcat ­ the online catalogue on Cataclysmic Variables

CVcat, a first version of an online catalogue on Cataclysmic Variables (CVs), was developed by the CV group in Gottingen and presented to the public in Ё August 2001 due to the increasing need in the community of CV researchers for an authoritative, up-to-date, online database of the relevant ob jects (Kube et al. 2003). In this catalogue some of the concepts of AstroCat are already realized. It comprises data from `classical' catalogues on CVs (mainly Ritter & Kolb 2003) as well as additional information compiled manually from numerous publications. Since the acceptance of CVcat in the CV community is good, we decided to re-implement the catalogue with additional features providing more flexibility and convenience to the users. For that purpose, we started to develop the AstroCat framework which is not only designed for the re-implementation of CVcat, but can also be used for the installation of catalogues covering different astronomical fields. Up to now, CVcat is used by 150 registered users and can be accessed at http://www.cvcat.org. The upgrade to the AstroCat -based version is planned for January 2004. A non-interactive demonstration of the new version can already be found at http://astrocat.uni-goettingen.de/cvcat-demo/. 3. Target Group

AstroCat is especially suited to set up databases used by relatively small research communities (several hundred users). Since all catalogue entries should be approved by editors, we estimate the maximum number of ob jects that can be handled properly to be several thousands. The possibility to comment on catalogue entries is particularly useful if extensive calculations and/or non-standard methods are required to derive the respective ob ject properties. 4. Technical Realization system. The is controlled ed internally be found on

The catalogue data is held in a PostgreSQL database management communication between the database and the webserver (Apache) by PHP scripts. Queries to and results from the database are handl in an XML dialect, AstroCatML3 , for which an XML Schema can
1 2 3

http://astrocat.uni-goettingen.de http://astrocat.uni-goettingen.de/#discussion http://astrocat.uni-goettingen.de/#astrocatml


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Stored in Filesystem Stored in SQL RDBS

Binary Files

Web Browser

Web Server

AstroCat Frontend

Catalogue Data

AstroCat Administration

AstroCat Backend

Catalogue Structure

Mail Client

Mail Server

User Data

Database Agents

HTML Data XML Data

ASCII Data SQL Data

Binary Data

Figure 2.

Software components and data flow in AstroCat.

our web page. A schematic view of the data flow in AstroCat can be found in Fig. 2. 5. Outlook

After the completion of CVcat we plan to transfer the new concept to a different field of astronomical research by installing a catalogue on extrasolar planets (EPcat) based on the AstroCat software. Furthermore, we will provide a registry where the metadata of all AstroCat -based catalogues can be stored, in order to establish interoperability mechanisms between catalogues, e.g. simultaneous searches. It is also intended to integrate the information provided by the catalogues based on AstroCat in the global network of Virtual Observatories. 6. Partners

AstroCat/CVcat is funded by the Deutsche Forschungsgemeinschaft (pro ject number LIS 4 - 554 95 (1) SUB GЁttingen). The pro ject is realized in colo laboration with the Niedersachsische Staats- und UniversitЁ bibliothek (SUB), Ё ats GЁ ottingen, in the framework of Virtuel le Fachbibliothek Astronomie. CVcat will be hosted at the SUB after completion. References Kube, J., Gansicke, B. T., Euchner, F. & Hoffmann, B. 2003, A&A, 404, 1159 Ё Ritter, H. & Kolb. U. 2003, A&A, 404, 301